· Important fixes for running as root systems with /dev/ptmx! Earlier versions screwed up permissions on /dev/ptmx on some systems, making a real mess.

· Other features useful for running as root: Can now set permissions on pty, and also chroot and switch UID/GID after opening devices.

· If permissions are set on the pty, create a process to monitor interceptty for exit, and when it finishes fix up permissions. This makes sure permissions get reset even if interceptty dies unexpectedly, and also allows us to reset a pty owner even if we've dropped privileges. This isn't necessary on modern systems, but doesn't hurt.